compiler-gcc.h: use "proved" instead of "proofed"

Link: http://lkml.kernel.org/r/1477894241.1103202.772260161.1B0A5995@webmail.messagingengine.com


Signed-off-by: Benjamin Peterson <bp@benjamin.pe>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>